Optical and thermal properties of luminescent Er3+-doped lithium tellurite glasses

The effects of Er3+ concentration on the short-range order, thermal and luminescence properties of lithium tellurite glasses (xEr(2)O(3)-24Li(2)O-(75-x)TeO2, x = 1-5 mol%) were studied by X-ray diffraction, density measurements, differential scanning calorimetry, UV-visible, Raman and photoluminescence spectroscopic techniques. The incorporation of 1-5 mol% Er2O3 in the lithium tellurite glass system increases density steadily from 4.97 to 5.21 g cm(-3), it decreases the average Te-O co-ordination number from 3.51 to 3.44 due to short-range structural transformation: TeO4 -> TeO3 units, and it enhances the glass transition temperature from 264 degrees C to 298 degrees C. The glass sample with 1 mol% Er2O3 produces maximum green light emission with 89% color purity and fluorescence quantum yield of 3.05%. On increasing the Er2O3 concentration from 1 to 5 mol%, very strong concentration quenching effects on the luminescence intensity are found.